kcov: remove pointless current != NULL check

__sanitizer_cov_trace_pc() is a hot code, so it's worth to remove
pointless '!current' check.  Current is never NULL.

Link: http://lkml.kernel.org/r/20170929162221.32500-1-aryabinin@virtuozzo.com
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Acked-by: Dmitry Vyukov <dvyukov@google.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kernel/kcov.c

@@ -62,7 +62,7 @@ void notrace __sanitizer_cov_trace_pc(void)
 	 * We are interested in code coverage as a function of a syscall inputs,
 	 * so we ignore code executed in interrupts.
 	 */
-	if (!t || !in_task())
+	if (!in_task())
 		return;
 	mode = READ_ONCE(t->kcov_mode);
 	if (mode == KCOV_MODE_TRACE) {